This invention relates to a self powered aquatic device that will tow a person through and across a water surface where in use most of the persons body is essentially in the water below the surface, but where the head and arms are supported above the surface, in a manner that could be described as a powered alternative to swimming but with a higher speed capability.
There are many varied vehicles or products designed for use on water, recreational or otherwise, ranging from various types of boats, powered sailing or rowing, to products towed by boats such as water skis, towable inflatable products and the like. Various other products powered or not, such as jet skis, surfboards, pedaloes, canoes, windsurfing boards etc. All these products are designed to essentially carry and propel someone over and across a water surface. There are even products that still essentially carry and propel a person, although the person is in contact with the water or partially submerged, such as U.S. Pat. Nos. 3,543,712 or 3,716,013, or British specification 795194 or P.C.T. publication W.O. 84101755.
As opposed to this concept of being carried and propelled over and across water, there are few products that actually tow a persons body itself directly in and through a water surface.
The few products designed to tow as exhibited by prior art take various forms, some of which are, a power unit attached to a framework and held above the water by a float or floats, towing a person behind (French No. 2625684), a power unit enclosed in a boat shaped box or hull, with a means of holding on (Japanese No. 2-126870 or British specification 1545222), or a device which is commercially available, a specially designed water sealed internal combustion engine operating direct in water, again with a means of holding on (U.S. Pat. Nos. 3,630,165 or 3,890,920). Generally, the majority and the earlier of prior art had the means of holding and controlling positioned at the rear of the device. This was a very tiring and sluggish means of steering. Later on it was found that positioning the means of holding and controlling at the front of the towing device (U.S. Pat. No. 3,890,920) was less tiring and a lot more accurate, despite the fact that with this system it is necessary to control whether the device is tilted in an upwards or downwards direction as well as steering from side to side.
Although these and other designs are different from each other, the basic overall concept of all prior art has been a separate towing device, towing a person along as a separate entity. Although an acceptable arrangement at normal swimming speeds, little or no consideration seems to have been given to the potential or possible capabilities of a towing device beyond simply motorising a swimmer, and in fact above normal swimming speeds, the arrangement is inherently hydrodynamically inefficient to the point of being self limiting, both in terms of performance or speed attainable, and also in the level of energy required from the user for the following reasons.
It is a well known and accepted fact that if a human body lying face down is moved forwards through water with the arms outstretched and the head raised above the water surface, most drag or turbulence in the water will occur around the persons upper chest and shoulders, caused by the relatively blunt shape of the persons frontal chest area and shoulders trying to push through the water. This is the reason why even at speeds as low as normal swimming, all professional and any serious swimmer will swim with their head down in an attempt to overcome this drag effect, only raising it momentarily in order to see and breathe.
Where a towing device is towing a person along as a separate entity, the necessity of the person being towed holding on to the device and consequently having their arms and chest submerged in the water while their head is raised and tilted upwards in order to see and breathe creates if any speed is involved, considerable drag or turbulence in the form of a "bow wave" around the upper chest and shoulders for the reasons already explained. As speed is increased, the "bow wave" becomes more pronounced and higher, having the effect of trying to drag the person being towed away from the device, tiring the persons arms in the process and causing the person to attempt to hold their head higher which creates an even more pronounced and high "bow wave", the only solution being to reduce speed.
All prior art where the only contact between the device and the person being toward is the persons hands holding on to the device, is inevitably tiring in use since any steering or directing, not just left or right but on some devices up or down as well, in order to maintain a desired driving angle or distance from the device, can only be accomplished by using the strength of their hands, wrists or arms.
A related effect which also causes tiring is that in normal sea conditions where waves exist, the level of the towing device bobbing up and down and that of the person being towed is constantly changing in relation to each other. In choppy water conditions, these changing levels can also means that the persons body can inadvertently partially block or get in the way of the propelling stream of water.
Finally, with prior art, the person's head is not positively supported above the water surface. In conditions not anticipated, such as rough sea, cramp, illness, fatigue, sickness or injury, the person must still make the relevant effort to hold their head above water.
In conclusion, although some are better than others, at any speed significantly above normal swimming speeds, all prior art requires considerably more energy and effort than necessary from the user, in order to steer or control, and to overcome the drag or turbulence around the person's chest area, in achieving what can only be a comparatively modest increase in sped before the self limiting effect inherent in the concept of a separate towing device and a separate user takes over.